Bottom Line:
Secretion is tunable and occurs both in vitro and in vivo.SOCS secretion into lung lining fluid was diminished by cigarette smoking in humans and mice.Secretion and transcellular delivery of vesicular SOCS proteins thus represent a new model for the control of inflammatory signaling, which is subject to dysregulation during states of inflammation.

Affiliation: Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and Department of Microbiology and Immunology, University of Michigan Medical School; and Department of Environmental Health Sciences, School of Public Health; University of Michigan, Ann Arbor, MI 48109.

fig8: SOCS secretion in the lung in vivo is regulated by immunomodulatory substances and dysregulated in association with cigarette smoking. (A) Mice (three per group) were subjected to intrapulmonary administration of 50 µl saline alone or saline containing 15 µg PGE2 and/or LPS. BALF was harvested 3 h later, pooled, concentrated, and subjected to WB analysis for SOCS3. (B) BALF from never smokers or healthy current smokers (n = 4 subjects per group) was concentrated and subjected to WB analysis for SOCS3 and SOCS1; results from three subjects per group are depicted, with each lane representing an individual subject (top); after densitometric analysis of blots from all four subjects per group, SOCS levels in BALF of smokers was expressed as a percentage of that in never smokers (bottom, left). SOCS3 levels were also determined by ELISA of sonicated BALF in n = 7 subjects per group (bottom, right); the mean level in never smokers was 0.26 ± 0.12 pg/µg protein, and that in smokers was expressed as a percentage of the never-smoker level. Error bars indicate SE. (C) Mice were subjected or not to 2 h/d of cigarette smoke for 3 or 7 d, and BALF from at least three mice in each group (as indicated by the individual lanes) was subjected to WB analysis for SOCS3; data at the bottom represent mean ± SE arbitrary densitometric units. *, P < 0.05 versus human never smokers (B) or unexposed mice (C). The blot shown is representative of two experiments (A), or the data are the mean from the number of human subjects (B) or mice (C) indicated.

Mentions:
We next asked whether SOCS secretion occurred in the lung in vivo and whether it was a regulated phenomenon, as was observed in vitro. SOCS3 could be readily identified by WB in concentrated bronchoalveolar lavage fluid (BALF) obtained from the lungs of individual naive mice (Fig. 8 A). In fact, quantitation of SOCS3 in sonicated BALF from naive mice (n = 10) by ELISA yielded a level of 10.38 ± 0.96 ng/ml, a concentration which substantially exceeds that reported for most cytokines. Furthermore, just as was observed in vitro, the level of SOCS3 in BALF increased and decreased 3 h after intrapulmonary administration of PGE2 and LPS, respectively, and an intermediate level was observed when they were co-administered (Fig. 8 A).

fig8: SOCS secretion in the lung in vivo is regulated by immunomodulatory substances and dysregulated in association with cigarette smoking. (A) Mice (three per group) were subjected to intrapulmonary administration of 50 µl saline alone or saline containing 15 µg PGE2 and/or LPS. BALF was harvested 3 h later, pooled, concentrated, and subjected to WB analysis for SOCS3. (B) BALF from never smokers or healthy current smokers (n = 4 subjects per group) was concentrated and subjected to WB analysis for SOCS3 and SOCS1; results from three subjects per group are depicted, with each lane representing an individual subject (top); after densitometric analysis of blots from all four subjects per group, SOCS levels in BALF of smokers was expressed as a percentage of that in never smokers (bottom, left). SOCS3 levels were also determined by ELISA of sonicated BALF in n = 7 subjects per group (bottom, right); the mean level in never smokers was 0.26 ± 0.12 pg/µg protein, and that in smokers was expressed as a percentage of the never-smoker level. Error bars indicate SE. (C) Mice were subjected or not to 2 h/d of cigarette smoke for 3 or 7 d, and BALF from at least three mice in each group (as indicated by the individual lanes) was subjected to WB analysis for SOCS3; data at the bottom represent mean ± SE arbitrary densitometric units. *, P < 0.05 versus human never smokers (B) or unexposed mice (C). The blot shown is representative of two experiments (A), or the data are the mean from the number of human subjects (B) or mice (C) indicated.

Mentions:
We next asked whether SOCS secretion occurred in the lung in vivo and whether it was a regulated phenomenon, as was observed in vitro. SOCS3 could be readily identified by WB in concentrated bronchoalveolar lavage fluid (BALF) obtained from the lungs of individual naive mice (Fig. 8 A). In fact, quantitation of SOCS3 in sonicated BALF from naive mice (n = 10) by ELISA yielded a level of 10.38 ± 0.96 ng/ml, a concentration which substantially exceeds that reported for most cytokines. Furthermore, just as was observed in vitro, the level of SOCS3 in BALF increased and decreased 3 h after intrapulmonary administration of PGE2 and LPS, respectively, and an intermediate level was observed when they were co-administered (Fig. 8 A).

Bottom Line:
Secretion is tunable and occurs both in vitro and in vivo.SOCS secretion into lung lining fluid was diminished by cigarette smoking in humans and mice.Secretion and transcellular delivery of vesicular SOCS proteins thus represent a new model for the control of inflammatory signaling, which is subject to dysregulation during states of inflammation.

Affiliation:
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and Department of Microbiology and Immunology, University of Michigan Medical School; and Department of Environmental Health Sciences, School of Public Health; University of Michigan, Ann Arbor, MI 48109.